Alfonso Martone from Italy has built a NXT Plotter that plots by making holes into the paper.
There must be other NXT-based plotters around - for instance, there's Andreas Dreier's Egg Plotter.
Do you know of other ones? If so, please comment!
There is the excellent plotter built by Anders (with building instructions!): http://www.norgesgade14.dk/legoSider/mindstorm_en.html
(didn't found how to get a direct link. Click on the lamp on top, then on the plotter thumbnail.
plotter.so i want to see how it works .